Basically, its co-ed volleyball & mud.  The specifics are laid out in a printable form here. The rules are subject to modification if necessary. Failure to adhere to the regulations of Oozeball, such as the waiver requirement, may result in disqualification. 

Oh, and the most important detail – there's a cash prize for the winning team!

*To display the rules, roster, or waiver form, you need the 
Adobe Acrobat Reader.